Detergent and wear inhibiting mineral lubricating oil compositions



Patented Nov. 1, 1960 DETERGENT AND WEAR INHIBITING MINERAL LUBRICATING OIL COMPOSITIONS John A. Edgar and Roland Frederick Bergstrorn, Martinez, and Robert Q Jones, Berkeley, 'Calif., assignors to Shell Oil Company, New York, N. Y., a corporation of Delaware No Drawing. Filed Sept. 26, 1955, Ser. No. 536,747

4 Claims. (Cl. 252-334) This invention relates to lubricating oil compositions and more particularly to highly detergent or dispersant lubricating oil compositions which also possess good extreme pressure properties and prevent wear.

Until recently, lubricating oil detergents generally employed were polyvalent metal salts or soaps of organic carboxylic acids, organic naphthenic acids, or organic sulfonic acids. Detergents of this type, although effective in engines operating at relatively high temperatures, are generally ineffective at low temperatures such as are encountered in engines operating under severe, stopand-go, conditions.

As obviating some of the shortcomings of the metallic detergents, it has been observed that certain oil-soluble non-ash synthetic polymeric compounds possess dispersant properties. Polymer compounds of this type range in molecular weight from about 1,000 to about 1,000,000, and preferably from about 30,000 to about 500,000 and can be represented to consist essentially of units of the general formula:

wherein the Xs can be the same or different polar groups such as is hydrogen or a short alkyl radical of not more than 4 carbon atoms and preferably an alkyl radical of from 1 to 3 carbon atoms; R can be the same as R or a long alkyl radical of 8 or more carbon atoms, and preferably from 14 to .18 carbon atoms or a basic group, e.g., (CH ),,N wherein n is an integer of 1 to 20, preferably of from 4 to 12; m can be Zero or one; X, can be the same as XR or a long alkyl radical of atleast 8 carbon atoms. At least one of the Rs should be a long alkyl radical of at least 8 carbon atoms.

Although polymers of the type mentioned above and which will be described hereinafter in greater detail impart excellent detergency to lubricants used over wide temperature ranges, they lack the desired property of inhibiting wear which is encountered in various types of engines operating under low and high temperature conditions and under heavy loads and extreme pressures.

A principal object of this invention is to produce a lubricating composition having desirable detergent or dispersant and anti-wear properties. Another object of this invention is to produce a lubricating composition suitable for use under stop-and-go driving conditions. These and other objects will be more fully understood,

and others will be apparent from the description of the invention.

It has now been discovered that the above and other objects can be attained by adding to a lubricating oil, a minor amount of an oil-soluble polar-containing polymeric detergent compound of the type mentioned above and represented by Formula I, and a minor amount of an oil-soluble highly basic metal salt of an organic sulfonic acid.

The imparting of anti-Wear properties to non-ash containing polymeric detergents, which lack this desired property, by highly basic metal sulfonates, which normally function themselves as detergents is unusual. The manner or mechanism whereby this additive combination functions in an oil is not clearly understood, but the unusual manner in which these two additives act, and the unexpected properties which they impart to oils have been evidenced by the results of extensive tests.

The oil-soluble polymeric detergents as represented by the general formula (I) can be characterized as polymers containing a non-polar oil-solubilizing group such as long chain alkyl radicals and polar active detergent groups of which preferred are the:

groups, wherein R is hydrogen or a long chain alkyl radical such as an alkyl radical of from 12 to 18 carbon atoms, and R, is a short alkyl radical of from 1 to 4 carbon atoms. It is preferred that the non-polar oilsolubilizing groups and the polar detergent groups be attached either directly or indirectly to different carbon atoms of a long hydrocarbon backbone chain as indicated in Formula I.

One class of preferred polymeric compounds which can be used in accordance with the present invention are suitably prepared as hydrolyzed or alcoholized copolymers of alpha-olefinic hydrocarbons, such as alphaalkenes containing from 10 to about 40 carbon atoms and preferably 12 to 30 carbon atoms, with hydrolyzable vinyl compounds, such as vinyl halides {vinyl chloride) and vinyl esters (vinyl acetate), or as copolymers of such alpha-olefins with other low molecular weight polymerizable polar-substituted alpha-alkenes, such as the acrylo compounds, as illustrated by acrylic acid, acrylonitrile, acrylarnide, methacrylic acid, methacrylonitrile, methacrylamide, as Well as mixtures and derivatives thereof. By alpha-olefinic hydrocarbons is meant herein hydrocarbons which contain a terminal ethenyl (-CH=CH group. Polymeric compounds of this class can be represented by the general formula consisting essentially of units of:

Y (II) wherein R is a long alkyl radical which can contain from 10 to 18 carbon atoms and Y can be:

0 ll H -OH, COOH, COOR, CN\, -CNR4N Normally, the reactants are copolymerized in the presence of a catalyst. The catalysts suitable for use in making the polymers and copolymers include various oxygen-yielding catalysts, for example, various organic peroxides, such as aliphatic, aromatic, heterocyclic, and alicyclic peroxides, such as diethyl peroxide, tertiary butyl hydroperoxide, dibenzoyl peroxide, dimethylthienyl peroxide, dicyclohexyl peroxide, dilauroyl peroxide and urea peroxide. These are mentioned by way of nonlimiting examples of organic peroxides suitable for use in the preparation of additives for use in compositions of this invention. Other catalysts include sodium bisulfite, diethyl sulfoxide, ammonium persulfate, alkali metal perborates, azo compounds such as alpha, alpha-azodiisobutyronitrile, etc.

- Copolymers of this invention can be prepared by any suitable means, such as described in US. Patents 2,421,971 and 2,467,774. They may also be produced by themethod described in US. Patent 2,551,643, followed by hydrolyzing the copolymer by the method described in the first two patents. Suitable copolymers also can be prepared by the method described in US. Patents 2,421,971, and 2,467,774, except that for vinyl esters, acrylonitriles, acrylamides, or acrylic acids are used or these copolymer-s can be prepared by the general method described in US. Patents 2,436,926, and

The following example illustrates suitable compounds and their preparation:

EXAMPLE I Hydrolysis product of alpha-octadecene-vinyl acetate copolymer About 1 mole of vinyl acetate and 1.2 moles of alphan-octadecene were thoroughly mixed, a small amount of benzoyl peroxide was added to the mixture and the resulting mixture placed in a glass bomb from which air was displaced by nitrogen. The bomb was placed in a water bath maintained at around 80 C. for a period of about 24 hours. The product was topped to 170 C. at 2 mm. of Hg pressure and on analysis the residue had an ester value of 0.491 gram-equivalents of ester groups per '100 grams of sample.

This product was alcoholized in about 1,800 ml. of methanol to which about 1 gram of metallic sodium was added. The mixture was distilled to remove the methyl acetate and the excess methanol and the product was then dispersed in heptane and topped. The resulting residue product was an alkanepolyol (polyhydric alkanol) having a molecular weight of about 8,000 as determined bylight scattering means. From the molecular weight and the aforesaid number of gram equivalents of ester groups per 100 grams of the ester, it can be calculated that for the alkane polyol there is a ratio of alcoholic hydroxyl groups to hydrocarbyl (hexadecyl) radicals of about 2.2. Furthermore, the average alkanepolyol molecule contains about 50 hydroxyethylene radicals and about 23 octadecylene-1,2 radicals; there is a total of about 73 hydrocarbyl and hydroxyl radicals per molecule. In other words, the molecule is a chain of 146 C-atoms having 50 hydroxyl and 23 hexadecyl radicals attached to 73 different C-atoms of the chain throughout the chain length. Those 73 C-atoms have attached thereto 73 H-atoms (one each) and the remainder of the C-atoms are saturated with 2 H-atoms each. The molecule can be represented by the formula:

Another class of polymeric detergents can be prepared by polymerizing unsaturated polymerizable heterocyclic nitrogen base compounds and derivatives thereof with another polymerizable unsaturated material free of heterocyclicnitrogen radicals, such as acrylic compounds, vinyl and vinylidine compounds, allyl compounds, or unsaturated polycarboxylic acids and the like. Polymers of this class can be represented by the general formula having units of:

-Hl( JR6oH-2 JR,- Z1 (1H) wherein Z is a basic heterocyclic nitrogen group such as 4 a C-pyridyl radical, Z is an oil-solubilizer polar group, e.g.,

CO R5 and R is hydrogen or a short alkyl radical and R is an alkyl radical. v The copolymers of this type can be prepared by any suitable means, the reaction preferably being carried out in the presence of a polymerization catalyst. Thus, the reactions in the mol ratio of 1:10 to 10:1 and preferably from 1:1 to 1:4 of a C-vinyl pyridine to other polymerizable material, e.g., acrylate can be reacted in the presence of from 0.1 to 5% of a catalyst such as a peroxide or azo compound in the presence or absence of an inert solvent such as a hydrocarbon under a blanket of nitrogen or carbon dioxide and at a temperature varying fromroom temperature or lower to about 180 C. or higher for a period of from about 2 to 48 hours until the average molecular weight of the copolymer exceeds 50,000 and preferably is within the range of from 75,000 to 700,000.

The following examples illustrate the preparation of polymeric compounds containing units of Formula (HI).

EXAMPLE II A mixture of about 1 mole of lauryl methacrylate, 1 mole of 2-methyl-5-vinyl pyridine and 0.4% wt. of benzoyl peroxide were placed in a suitable reaction vessel and the mixture reacted for a period of over 2 hours at -85 C. in a nitrogen atmosphere. The unreacted materials were stripped off at 185 C. and 1 mm. pressure and the resulting copolymer was a rubbery product containing around 3% nitrogen, having a molecular weight in excess of 150,000, and was soluble in hydrocarbon oils.

EXAMPLE III A copolymer of lauryl methacrylate and Z-methyl-S- vinyl pyridine was prepared by the method of Example II, but in which the mole ratio of the reactants was 4 to 1, respectively. The nitrogen content of the product was about 2%, the molecular weight was in excess of 75,- 000, and it had a sticky rubbery consistency but was oil soluble.

Still another class of polymeric detergents can be represented by the formula having repeating units:

CHz-CRr-CHr-(ER wherein D is a polar radical such as where R; is a long alkyl radical, e.g. C -C alkyl radical, and E is a basic radical, e.g.,

0 R4 i JO-R4N and R is the same as in Formula III; Polymers of this type can be prepared by the methods described in US. Patents 2,584,968, 2,666,044, and 2,680,717, and include lauryl methacrylate/diethylamino ethyl methacrylate (:10) copolymer lauryl methacrylate/styrene/dibutylaminoethyl methacrylate, lauryl methacrylate/4-dimethylaminocyclohexyl methacrylamide (90/ 10), lauryl methacrylate/tertoctaylaminoethyl methacrylate, and mixture thereof.

The second essential additive used in compositions of this invention which imparts wear inhibiting properties to said compositions is a highly basic metal salt of an organic sulfonic acid. By basic salts is meant that the amount of neutralizing agent used is far in excess, namely, in the range of from 30 to 1000, and preferably between asseeso" 5 50 and 800 percent in excess of that normally required to neutralize the acid to produce the normal salt.

The basic sulfonates can be derived from any suitable material and prepared by any of the Well-known methods. Preferred materials for making sulfonates include liquid petroleum fractions, alkyl substituted aromatic compounds and alkyl substituted polar-containing aromatic compounds. Although various basic metal sulfonates are contemplated for use in compositions of this invention, the basic sulfonates of the metals of group II of the periodic table having an atomic number of from 12 to 56 inclusive, are preferred, and especially the alkaline earth metals (Ca, Ba, Mg, or Sr) Within that group of metals. Basic sulfonates suitable for use in compositions of this invention are described in US. Patents 2,501,732, 2,585,520, 2,623,016, 2,678,301, 2,- 695,273, 2,695,910, 2,708,182, as Well as the basic sulfonates described in the French Patent 1,060,826, and the German Patent 881,653. Specific basic sulfonates Which are useful in compositions of this invention include basic calcium, barium, magnesium, strontium, and lead petroleum sulfonates, of oil-soluble petroleum sulfonic acids, tetra-tertiarybutyl-naphthalene sulfonates, di- Waxbenzene sulfonates, stearyl benzene sulfonates, diwaxnaphthalene sulfonates, ditertiary amyl phenol sulfonates, and mixtures thereof.

To compositions of this invention can be added auxiliary additives such as anti-oxidants or corrosion inhibitors of which organic compounds containing inorganic phosphorus acidic radicals are particularly preferred. Compounds of this type can be obtained by reacting monoor polyhydroxy or merc-apto organic compounds, aliphatic olefins, e.g., isobutylene, cyclic olefins, e.g., terpenes, and mixtures thereof, with P POClg, P 5 P501 or P Se salts of said products are also included and are obtained by neutralizing the reaction products mentioned with oxides, hydroxides, carbonates, or halides of alkali, monoor polyvalent metals such as the alkali, alkaline earth or heavy metals exemplified by Na, K, Ca, Ba, Sr, Mg, A1, C0, Pb, Ni, and Fe, to form the corresponding salts and mixtures thereof. Compounds of this type include salts such as Na, Ca, Ba, Zn, and Al salts of alkyl, alkaryl, aralkyl, cycloalkyl, aryl phosphates, thiophosphates, and specifically illustrated by Na,

K, C-a, Ba, Zn, and Al methylcyclohexyl phosphate, dimethylcyclohexyl dithiophosphate, dihexyl acid thiophosphate, lauryl benzyl thiophosphate, butyl trichloromethane phosphonate; P S -olefin reaction product as described in U.S. Patents 2,316,080, 2,316,082, 2,316,086, 2,261,047, 2,540,084, 2,358,305, 2,466,408, 2,344,393, 2,493,217, and 2,662,856, as well as the non-salt or nonneutralized products such as P S -te1-pene reaction products and mixtures thereof. Compounds of this type are available commercially under the trade names of Lubri- Zol 304, or 1060 (Lubri-Zol Corp); Aerolube 70 (American Cyanamid Co.); Stan-Add 48 (Standard Oil Co. of Indiana); and Santolube 394C (Monsanto Chemical Co.). Other phosphorus compounds which can be used are of the type described by Smalheer et al. in Petroleum Processing, December, 1952. A particularly preferred list of such compounds includes the Zn and Ba salts of alkyl dithiophosphate, Na, K, and Ba salts of P S -polybutene reaction products and/or P S -terpene (pinene) reaction products, said products being commercially available from Lubri-Zol Corporation, Standard Oil Company of Indiana, and Monsanto Chemical Company, respectively, under the trade names of Lubri-Zol 304, and Lubri-Zol 1060; Stan-Add 47, 48, and L-9l03; and Santolube 394-C.

Lubricating oils for additives of this invention can be any natural or synthetic material having lubricating properties. Thus, the base may be a hydrocarbon oil of wide viscosity range, e.g., 100 SUS at 100 F. to 150 SUS at 210 F. The hydrocarbon oils may be blended with fixed oils such as castor oil, lard oil, and the like, and/ or with synthetic lubricants such as polymerized olefins, copolymers of alkylene glycols and oxides; organic esters of poly-basic organic and inorganic acids, e.g., di-Z-ethylhexyl sebacate, dioctyl phthalate, trioctyl phosphate; polymeric tetrahydrofuran; polyalkyl silicone polymers, e.g., dimethyl silicone polymer, and the like. If desired, the synthetic lubricants may be used as the sole base lubricant or admixed with fixed oils and their derivatives.

Mineral lubricating oils which are particularly desirable for use in compositions of this invention and which have been used as a base for the compositions of this invention were obtained from West Texas Ellenburger crudes, East Texas crudes, Oklahoma crudes, California crudes. A useful refined oil therefrom, had the following properties:

Gravity, API Min. 26.5 Pour point, F. Max. 10 Flash, COC, F. Min. 390 Viscosity, SUS at F. -460 Viscosity index Min. 95

Another such oil is an SAE 30 mineral oil having the following properties:

Gravity, API Min. 24.5 Pour point, F. Max. 5 Flash, COC, F. Min. 415 Viscosity, SUS at 210 F. 58-63 Viscosity index 50-60 The general formulations of compositions of this invention can be represented by:

Preferred compositions of this invention are illustrated by the following compositions:

COMPOSITION A Copolymer oflauryl methacrylate/diethylamino ethyl methacrylate (90:10) 5% Wt.

Basic calcium petroleum sulfonate 0.5% sulfate residue. Zn dialkyl dithiophosphate 0.8% wt. Mineral lubricating oil (SAE 30) Balance.

COMPOSITION B Copolymer of laurylmethacrylate/2-methyl-5- vinyl pyridine (4:1) 2% wt. Basic calcium petroleum sulfonate 2% wt. Mineral lubricating oil Balance.

COMPOSITION C Hydrolyzed copolymer of octadecene-l/vinyl acetate 2%. Basic calcium petroleum sulfonate 2%. Mineral lubricating oil Balance.

COMPOSITION D Copolymer of octadecyl methacrylate/Z-methyl-5-vinyl pyridine (4:1) 2% wt. Basic calcium petroleum sulfonate 2% Wt. Mineral lubricating oil Balance.

Other examples of compositions of this invention include mineral lubricating oils of the SAE 10, 20, 30, or 10W-30 type containing from about 1% to 6% by weight of copolymers of lauryl methacrylate/styrene/dibutylaminoethyl methacrylate, lauryl methacrylate/4-dimethylamino-cyolohexyl methacrylamide; lauryl methacrylate/Z-niethyl-S-vinyl pyridine, lauryl methacrylate/ 2-ethyl-5-vinyl pyridine, lauryl methacrylamide/ 2-methy1- 5-vinyl pyridine, hydrolyzed copolymer of hexadecene- 1/vinyl acetate and mixtures thereof; and from about 0.5% to about 5% by weight of oil-soluble basic calcium or barium petroleum sulfonate, diwax benzene sulfonate and mixtures thereof. To any of these compositions can be added in amounts of from about 0.1% to about 1% other additives, such as metal dithiophosphates (Zn dialkyl dithiopliosphat-e), metal thiocarbamates, such as zinc 'dibutyl dithiocarbamate, amines, such as phenylalpha-naphthyla-mine octadecylamine; viscosity index and pour point depressants, such as the Acryloids, and specifically, Acryloid, 150, 618, 710, and/or 768, made by Rohm and H-ass and described in US. Patent 2,710,842; condensation product of chlorinated parafiin wax and naphthalene; extreme pressure agents, such as oil-soluble polyhaloalkanephosphono components, such as 'trichloromethanephosphonic acid, esters, amides, or amine salts thereof, such as di-Z-ethylhexyl amine salt of trichloromethanejphosphonic acid; organic sulfides, and mixtures thereof.

The outstanding properties of compositions of this invention were demonstrated when Composition A was tested in a Chevrolet engine under EX-3 test procedure and at the end of the test, the engine was clean, no sign of wear or corrosion was noted, no piston rings were stuck, and the engine was in excellent condition. On the other hand, when the basic calcium petroleum sulfonate was omitted from Composition A, or replaced with an equal amount of neutral Ca petroleum sulfonate (identified as Compositions X and Y, respectively) and tested under equivalent conditions, the engine in each case was in poor condition as shown by the presence of several stuck rings and considerable Wear of engine parts was evidenced.

Similar results as with Composition A can be obtained with Compositions B, C, or D, or other compositions of this invention in the EX-3 engine test procedure.

Compositions of this invention can be used as engine oils, turbine oils, gear oils, and various other fields of lubrication where detergency and wear inhibiting properties are essential.

We claim as our invention:

1. A lubricating oil composition comprising a major amount of mineral lubricating oil and a minor but detergent amount of an oil-soluble copolymer of an acrylate ester of an acrylic acid and a long chain aliphatic alcohol 8 and a vinyl pyridine in the mol ratio of 1:1 to 10:1 respectively and having a molecular weight of from 50,000 to 700,000 and a minor, but wear inhibiting amount of an oil-soluble basic alkaline earth metal petroleum sulfonate containing from to 800% excess base.

2. A lubricating oil composition comprising a major amount of mineral lubricating oil and a minor but detergent amount of an oil-soluble copolymer of lauryl methacrylate and a vinyl pyridine in the mol ratio of 1:1 to 10:1 respectively and having a molecular weight of from 50,000 to 700,000 and a minor but wear inhibiting amount of an oil-soluble basic alkaline earth metal petroleum sulfonate containing from 50% to 800% excess base.

3. A lubricating oil composition comprising a major amount of mineral lubricating oil and a minor but detergent amount of an oil-soluble copolymer of lauryl methacrylate and 2-methyl-5-vinyl pyridine in the mol ratio of 1:1 to 10:1 respectively and having a molecular weight of from 50,000 to 700,000 and a minor but wear inhibiting amount of an oil-soluble basic calcium petroleum sulfonate containing from 50% to 800% excess base.

4. A lubricating oil composition comprising a major amount of mineral lubricating oil and a minor but detergent amount of an oil-soluble copolymer of octadecyl Inethacrylate and 2-methyl-5-vinyl pyridine in the mol ratio of 1:1 to 10:1 respectively and having a molecular Weightof from 50,000 to 700,000 and a minor but Wear inhibiting amount of an oil-soluble basic calcium petroleum sulfonate containing from 50% to 800% excess base.

References Cited in the file of this patent UNITED STATES PATENTS 2,584,968 Catlin Feb. 12, 1952 2,629,693 Barton et al Feb. 24 ,1953 2,666,044 Catlin Jan. 12, 1954 2,723,236 Assetf Nov. 8, 1955 2,737,496 Catlin Mar. 6, 1956 2,794,829 Van Der Waarden et a1. June 4, 1957 2,800,450 Bondi et al July 23, 1957 2,800,452 Bondi et al July 23, 1957 2,800,453 Bondi et al July 23, 1957 2,839,470 Warren et al June 17, 1958 2,865,956 Ellis et a1 Dec. 23, 1958 OTHER REFERENCES A New Class of Polymeric Dispersants for Hydrocarbon Systems, presented at American Chem. Soc. Meet., Kansas City, Mo., Mar. 23 to Apr. 1, 1954, pages 6 and 7. 

1. A LUBRICATING OIL COMPOSITION COMPRISING A MAJOR AMOUNT OF MINERAL LUBRICATING OIL AND A MINOR BUT DETERGENT AMOUNT OF AN OIL-SOLUBLE COPOLYMER OF AN ACRYLATE ESTER OF AN ACRYLIC ACID AND A LONG CHAIN ALIPHATIC ALCOHOL AND A VINYL PYRIDINE IN THE MOL RATIO OF 1:1 TO 10:1 RESPECTIVELY AND HAVING A MOLECULAR WEIGHT OF FROM 50,000 TO 700,000 AND A MINOR, BUT WEAR INHIBITING AMOUNT OF AN OIL-SOLUBLE BASIC ALKALINE EARTH METAL PETROLEUM SULFONATE CONTAINING FROM 50% TO 800% EXCESS BASE. 